Do something every time a module is imported

Question

Is there a way to do something (like print "funkymodule imported" for example) every time a module is imported from any other module? Not only the first time it's imported to the runtime or reloaded?

Answer 1

One possibility would be to monkey patch __import__:

>>> old_import = __import__
>>> def my_import(module,*args,**kwargs):
...   print module, 'loaded'
...   return old_import(module,*args,**kwargs)
...
>>> __builtins__.__import__ = my_import
>>> import datetime
datetime loaded
>>> import datetime
datetime loaded
>>> import django
django loaded

It worked fine on command line (using Python 2.7.3 on Windows XP), but I dunno if would work in other environments.

To access the module object (instead of just the module name - so you can do something useful with it) just intercept the return value instead of the argument:

>>> def my_import(*args,**kwargs):
...   ret = old_import(*args,**kwargs)
...   print ret
...   return ret
...
>>> __builtins__.__import__ = my_import
>>> import datetime
<module 'datetime' (built-in)>
>>> import django
<module 'django' from 'C:\Python27\lib\site-packages\django\__init__.pyc'>

Update: Just confirmed it works if used inside a python file too - though in this case, the correct way of assigning it is __builtins__['__import__'] = my_import.